Radio apparatus



Jam 17, cw. HICKS 2,144,39

RADIO APPARATUS Original Filed July 12, 1935 3 Sheets-Sheet l c. w. HICKS Jam. 17, 1939.

RADIO APPARATUS Original Filed July 12, 1935 3 Sheets-Sheet 2 OIQOOJ 02$ 85 6% f 0Q KQPQM Em d3 owem omm Q 4 3% w .w c can A 0 22h emu. on 25 :2 our Omn- C. W. HICKS RADIO APPARATUS Jan 17, 1939.

5 Sheets-Sheet 3 Original Filed July 12, 1955 330340350 o w an 50 o IIIIIIIIIIIIIIIIIIII-IIIIIIINIIIIIIIIIIIIIIIIII Patented Jan. 17, 1939 PATENT OFFICE RADIO APPARATUS Charles William Hicks, Washington, D. 0., as-

signor, by mesne assignments, to Bendix Radio Corporation, New York, N. Y., a corporation of Delaware Original application July 12, 1935, Serial No.

31,084. Divided and this application January 18, 1936, Serial No. 59,771

7 Claims.

This application is a division of my copending application Serial No. 31,084, filed July 12, 1935.

This invention relates to radio apparatus generally. More particularly, this invention relates to radio receiving apparatus adapted for obtaining bearings, determining direction, courses, positions, and the like with respect to one or more transmitting stations.

An object of this invention is to provide a circuit arrangement for controlling the reception of a conventional radio receiver and for permitting uni-directional, bilateral directional, and for omni-directional reception over said radio receiver. Another object of this invention is to provide an attachment for a conventional radio receiver whereby the directional receiving characteristics of said radio receiver may be changed at will.

Still another object of this invention is to provide an indicator arrangement for a directional antenna employing a rotatable scale and an adjustable mask adapted to be adjusted over portions of the scale when said directional antenna is being used for determining direction of signaling stations with respect thereto.

A further object of this invention is to provide a scale rotatable with a rotatable directional antenna and a mask for said scale, said mask being adjustable to cover a portion of the scale for the purpose of assisting the operator in using the directional antenna in making signal direction observations.

Other and further objects of this invention will be apparent to those skilled in the art to which it relates, from the following specification and the claims.

In accordance with this invention I provide a circuit arrangement which employs a dual type tube, having a pair of input circuits, one of which is connected to a directional antenna and the other of which is connected to a substantially non-directional antenna. I also provide means to the input or output circuits of each of the sections of the dual tube for controlling the amplifying characteristics thereof and for blocking either one of these sections at will so that signal energy from either the directional antenna or non-directional antenna or from both antennas may be impressed through said dual tube upon an amplifying and/or detecting circuit of a radio receiver.

I have shown the antenna coupling circuit, including the dual tube as a separate unit attachable to any conventional radio signal receiver, however, it is apparent that this coupling circuit may be incorporated into the receiver and employed as the first stage radio frequency amplifier or detector of said receiver. It is, of course, also obvious that the tubes need have no amplifying characteristics but may act merely as a coupling device. In practice, it is generally desirable to reduce the intensity of the signal component impressed upon the tube from the nondirec-tional antenna and increase the intensity of the signal component impressed upon the other tube from the directional antenna in order to balance the maximum signal intensities derived from both antennas. For this purpose one of the tubes, that is the section connected to the directional antenna is controlled by proper bias potentials to act as a relatively eflicient amplifier, while the other tube is adjusted to act more or less as an inefiicient amplifier or coupling unit. The signal intensities derived from the directional and non-directional antennas are thus conveniently equalized.

The signal components obtained from the directional and non-directional antennas are impressed upon a common circuit in the output circuits of the tubes and the resultant is a substantially uni-directional signal characteristic.

It is, of course, possible to amplify the outputs of the two tubes separately before impressing the signal components therefrom on a common circuit and likewise it is also possible to use a dual type tube having two triode sections instead of separate tubes in separate envelopes, as such dual tubes are well known in the art.

The operation of this invention will be more clearly understood from the following detailed description and the drawings in which, briefly, Fig. 1 illustrates a schematic diagram of connections of an embodiment of this invention; Figs. 2 and 3 illustrate the manual controls and cabinet ior housing the apparatus connected in accordance with the diagram of Fig. 1; Fig. 4 is a sectional view along the line l@ of Fig. 2; Fig. 5 is a sectional view along line 55 of Fig. 2; Fig. 6 is a sectional view along the line 6-15 of Fig. 4; Fig. '7 is a. sectional view along the line 'l'! of Fig. 5 and Figs. 8 and 9 are exploded views of the scale and mask. Referring to- Fig. 1 in detail, reference numeral I designates a metal cabinet or shield for housing the vacuum tubes 3 and 4, each employing a cathode, grid or control electrode and an anode. A heater filament such as 36 is used to heat the cathodes of both of these tubes 3 and 4. The grid electrode of tube 3 is connected to the connector or slip ring 7 of the loopantenna 5 through a suitable brush or similar contact. This loop is partially enclosed in a tubular screen or shield of metallic material for electrostatically shielding the conductors thereof. One end of the loop is connected to the slip ring 6 and the other end is connected to the slip ring 'I. The rings 6 and I are connected to one end of the inductance 8 and to the condensers 9, ID, I I, I2, and I3. The ring 6 is also grounded to the frame, chassis, or cabinet.

shown, however, multiple contact switches I4 and I5 are employed to control the connections between the inductance 8, and the condensers II), II, I2, and I3, and the loop, whereby a plurality of circuit combinations may be obtained between the loop, the inductance and the condensers for extending the tuning range thereof.

Taps of the inductance 8 are connected to dif ferent contact points of the switch I4 for the purpose of enabling the operator to use all or only certain parts of this inductance at one time. A plurality of adjacent contacts of the switch I4 are connected together into a unit and this unit is connected to the variable condenser I6. Likewise a series of the contacts of the switch I5 are connected together, as shown, and this unit is connected to a similar unit of switch I4 which isconnected to the'condenser i0. Three contacts of switch I5 are connected to the condensers II, I2, and I3, respectively; these latter contacts correspond in position to the contacts of switch I4, which are connected to the condenser Ill and the contacts of switch I5 that are connected to the condenser I correspond to the contacts of switch I4 that are connected to sections of the inductance 8. The switches I4 and I are mounted in tandem to be controlled by a single shaft, knob, handle pulley, gear or similar device, either manually or by some remote control mechanism.

Switches 23 and .24 are also mounted in tandem or in any other desirable manner to be controlled simultaneously as a unit for the purpose more fully described in the following paragraphs.

The antenna I6 is connected to the resistance I'!, which is enclosed in the metal shield I8 together with the switch IS. The switch I9 is provided with a plurality of contacts, two-of which are connected to the grounded end of resistance I'I, one to the antenna end of the resistance I1 and one to a variable contact on said resistance. The contact arm of the switch I9 is connected to the grid electrode of the tube 4.

The plate electrodes of the tubes 3 and 4am connected together by a series of resistance units 20, 2|, and 22. A condenser 25 is also connected between these plate electrodes. Multiple contact switch 23 is connected across the resistor 2I in such a manner that this switch short circuits this resistor in three positions of the contact' arm thereof. The switch 23 is arranged to be rotated in step with the switches I4, I5, and 24, and these switches are all illustrated with their contacts in proper relation with respect to the contact arms thereof. Thus rotation of the com: mon shaft of these, switches establishes the proper circuit connections in these switches simultaneously. The switch 24 is employed to close the circuit between two contacts of the switch 30 to enable this switch to short circuit the cathode resistor 33 when the switch 29, which is mounted in tandem with the switches I9 and 30, is in the position designated D in Fig. 2.

The switch 30 is connected to' the cathode "of the tube 4 to control the biasing potential of the The condenser 911s}? permanently connected across the loop 5, as

is connected to the cathode of tube 3.

grid electrode of this tube with respect to the cathode. Two of the contacts of this switch are connected to the negative terminal of the plate power supply leads 38. The terminal R of switch 29 and the tube heater filament 36 are also connected to this negative power supply terminal as shown in Fig. 1 of the drawings. As described above two contacts of switch 33 are connected to the switch 24, one to the contact arm and tacting arms of these switches are in positions shown in the drawings, they cooperate to short circuit the resistor-33.

Another resistor 32 is connected in series with the resistor 33 and this series is shunted by a fixed by-pass condenser 3I. A similar series of resistors 27 and 28, shunted by a condenser 26 The contact arm of switch 29 and the end contact B are connected to the resistor 21 in such a Way that this resistor is short-circuited when the switch arm of this switch is in contact with the terminal B.

Resistor 56 is connected in series with the positive power supply lead 38 to the resistances 2| and 22 connected between the plates ofthe tube. Another resistance 34 and fixed condenser 35 are connected to the resistances 2I, 22, and 36 to form a shunt circuit between these'resistances andthe ground, which may be the metal cabinet, chassis and the like. Resistor 31 is connected in series with the filament 36 and the heating current power, supply terminal 39; this resistor is also connected to the chassis as shown.

The output or plate circuits of the tubes 3 and 4 are coupled to the input circuit of the signal receiving apparatus M by the condenser 40 and the leads connected thereto, all of which are enclosed in suitable metal shields. The condenser 40 may be connected to the antenna binding post, connected to a radio frequency amplifier, of a conventional radio receiving set or it may be connected to the input circuit of the detector tube of a signal receiver. Where desired, the tubes 3 and 4 may be selectively operated as detectors and the output thereof fed into an audio frequency amplifier through the condenser 40. In either case the telephone receivers 42 or similar translating or indicating devices are connected to be energized in accordance with signal energy.

The apparatus schematicallyillustrated in Fig. 1 is assembled into the cabinet, preferably of metallic material, such as, copper or aluminum, shown in front vertical elevation in Fig. 2. The

' loop antenna container 5a is mounted on the top of the cabinet and is rotatable with respect to the cabinet. Any convenient form of mounting for the loop housing 5a, so that it may be rotated with reference to the cabinet, may be employed. However, the mounting most readily adopted is a simple friction fit of the bottom tubular'end of the loop housing into a hollow bearing formed in the top of the cabinet. The circular scale-carrying member 43 is attached to the loop housing 5a and is rotatable with the loop. This circular member 43 may be employed to rotate the loop when such rotation is accomplished manually, and may be employed in conjunction with a suitable screw operated clamp 46, which is adjusted by the thumb screw 45, to lock the loop in place and prevent its rotation. This clamp 46 is particularly useful when it is des red to shift the 'scalemask 44 to a certain position for the purpose of covering a certain part of the scale.

An index or pointer 44a is attached to the cabinet I adjacent to the scale of the member 53. A hollow dome 41, also of metal, is removably held over a hole in the top of the cabinet to cover the top of the tubes to permit easy access thereto. Suitable spring and pin members 48 and 49' are attached to the cabinet and the dome 41, respectively, and cooperate together to hold the dome in place.

A control 50 is attached to the front of the cabinet and is connected to the contact arm Ila of the resistance I! for the purpose of controlling the intensity or amplitude of the signal obtained from the antenna I6 when the switch I9 is in the position illustrated in Fig. 1, that is, the position corresponding to the position D of switch 29, which is connected in tandem with switch I9 and is operable by the knob 29a. A switch preferably of the toggle type, is mounted on the front of the cabinet and is connected into the leads 38 as shown in Fig. 1. A plate 52 having inscribed thereon brief instructions for operation of the unit, is attached to the front of the cabinet.

The knob Ma is employed to control the position of the tandem mounted switches M, I5, 23, and 24.

The knob Ma may be set in any one of seven positions, each of which corresponds to one of the contacts of each of the tandem switches that this knob controls. The primary purpose of this control is to select the signal frequencies to which the vacuum tube circuit is to respond and each setting of this knob is accordingly calibrated in accordance with a predetermined frequency band. The position occupied by the pointer of the knob Ma corresponds to the position of the contact arm of switch M.

The dial 9c is used to control the position of the rotary plates of condensers 9 and ID. A lockingclamp 91) is attached to the front of the cabinet and after the dial 9a and condensers are adjusted to the proper setting the thumb screw'9c may be tightened to clamp the dial in place to prevent further rotation thereof until the tension of the clamp is released A plug receiving socket 53 is attached to a side of the cabinet I for the purpose of facilitating making connections with an external power supply. A panel 54 of insulating material is supported inside of the socket 523 and connections 38 and 39 are supported on this panel. Binding post [6a is provided for connecting the antenna 16 to the unit and the coupling member 55 is employed to couple the unit to a shielded conductor connected to the conventional signal receiver input circuit. 1

The scale and scale mask carried by the stem of the loop antenna housing are illustrated in detail in Figs. 4, 5, 6, '7, 8, and 9 of the drawings. The dial 43 consists of a circular member fitted around the stem of the loop housing 50. in such a manner that the loop may be turnedmanually by engaging the periphery of the dial. The loop stem is provided on the inside with a suitable ceramic insulator 5b to space the loop conductors 5c. Arrows 43b are engraved on the top of the dial and point in a direction parallel to the plane of the loop.

Fig. 5 shows a bottom view of the'scale dial 54 and mask 44. Mask 44 has a cut-away section 4417 which extends over approximately half its .circumference and whenthis cut-away por-' The selector 29a is set on the position R wherein the loop tube section 3 is blocked through switch 29 applying proper bias to that section.

Omnidirectional signal energy is then transferred from the non-directional antenna to the receiver or amplifier 4| through tube section 4, antenna connection 16A, switch I9, condenser 40, and coupling connection 55.

The selector 29a is then set on position T, and while the frequency band selector Ma is on one of the four positions adjusting the loop tuning circuit to one of. the signal frequency channels between 500 and 8000 kilocycles, the tuning dial 9a is adjusted to tune in a continuous wave carrier, such as is transmitted by a broadcasting station, In this position, switch 19 is connected to a contact that is grounded and the cathode of tube 4 is connected to the filament 36. This tube 4 is thus blocked and is unaffected by signal energy.

The dial 9a is next adjusted until maximum signal strength is obtained through tube 3, using the loop 5' as the signal pick-up. The loop is moved angularly, to the position of maximum signal intensity and acts in the conventional way as a bilaterally selective pick-up.

The knob 29a is then turned to the position D. The loop is then rotated to determine whether or not signals of high intensity are received at one or two positions thereof. If two such positions are obtained, the loop is set in the position at which the weaker of the two high intensity signals is obtained and the control 50 for manipulating the contact [1a is operated until this weaker of the two high intensity signals either disappears or becomes very weak. The loop is then rotated 180 more or less, to the other of the two high intensity signal positions and the signal receiving unit is operated as a uni-lateral receiver employing the loop and the non-directional. antenna in equalized and balanced relation.

If the antenna I6 is not of the correct proportions to enable the proper signal intensity balance to be obtained, as outlined above, condenser 20a connected into the circuit, is varied until the weaker of the two high intensity signals disappears. The signal pattern of the antenna system, including the loop and the antenna I6, is then cardiodal or substantially so.

The unit of my invention may be operated as a bi-lateral direction finder in the following manner: The knob 29a is set on position R and the receiver dial operated to tune the receiver to a station. Next this knob 29a is set on position T and the loop is employed as a pick-up without the antenna H5. The loop is tuned by means of dial 9a and then the switch knob 29a is set on position D. The loop is then turned to the position giving the strongest signal and held in this position by turning the thumb screw 45 of the lock clamp which engages a section of the dial 43 and prevents rotation thereof and the loop. The mask 44, which is carried by the dial 43, as shown in the detail views Figs. 5, 6, and 7,

and the exploded views Figs. Band 9, is rotated until the zero index reference 44c coincides with the index pointer 44a, mounted on the ton of the cabinet. 7

I The knob 29a is then set on position 13, and the unit is operated as a bi-lateral directional. receiver. The loop is then unlocked by manipulation of thumb screw 45 and'swun'g to a minimum signal position with an unmasked portion of the arranged in. such away that after adjustment of mask 44 on the D position as describedthen the unmaskedsection ofthe scale 43a is in view when the minimumsignalis being received from a transmitting station located in the directionof the head or front of the ship.

When it is desiredto take very accurate bearings with the apparatus of my inventionv on an aeroplane, the loop should be'adjusted sothat a signal dead ahead will have a zero signal at zero on the azimuth dial 43 and a correction curve 'may beplotted to take care of deviations 'due to the influence of the plane structure.

happen that the unit is not mounted exactly in the proper location and a signal from a station known to be dead ahead gives a bearing that reads readjusted to read zero by loosening the three screws43c onthe top of the dial to read Zero by some few degrees from zero the dial may be moving the dial, until the readingis on zero while the loop is held in the position of minimum signal reception. The screws should be loosened only a very slight amount and carefully tightened after the dial is readjusted. A total motion of ten degrees in either direction is permitted by the mounting slots in the dial. If the error is more than ten degrees the entire unit ,must. be

re-aligned with the center line of the plane.

In addition to the operation of the unit as a rotating loop direction finder it may be used in a fixed position for homing. For this purpose the procedure is the same as for the operation as a rotating loop except that the loop is locked with the dial at zero over the index pointer and the ship is swung instead of the loop. The direction must be obtained on the D position and then the selector set to B when the pilot merely needs to keep the signal at the correct minimum to know that he is headed for the station.

In some cases, particularly at the higher frequencies it will be found that very accurate bearings may be obtained on the D position. In order to obtain the bearing relative to the plane heading when on the D position the mask is adjusted as described above and the bearing is read from the azimuth dial over the pointer onthe right hand end of the unit. An even more rapid but less accurate method is merely to note the position of the arrows 43b engraved on the top of the dial or, more easily still, note thatthe side of the loop painted in the lighter coloralways points toward the station when the loop is swung to the maximum signal on the D position.

For the taking of accurate bearings at high frequencies it is essential that the plane be at an The mask 44 is made with Should it 2;144,soe:

altitude suflicient that the curvature of the earth does not intervene between the plane and the transmitter. I At a distance of 100 miles the plane must have approximately 9000 feet altitude in order'to obtain good bearings. Useful directions on the D position may be obtained under average conditions at altitudes down to 5000 feet but on the B position the signal minimum isnot clearly defined and tends to vary in apparent direction at altitudes less than 9000 feet. This example set forth herein may be devised within the scope and spirit of this invention, and it is, therefore,

not desired to limitthis invention to the exact details set forth in the foregoing specificationexcept insofar as these details may be defined by the appended claims.

This application is a division of my copending.

application Serial No. 31,084 filed July 12, 1935, for Radio apparatus.

What I claim and desireto secure by Letters:

I Patent of the United States is as follows:

1. In direction finders the combination of av rotatable directional antenna, a substantially I non-directional antenna and means connected to said directional antenna and said substantially,

non-directional antenna for obtaining bearings and direction with respect to predetermined transmitting stations, a scale-carrying member attached to said directional antenna and ro-- tatable therewith, and, a mask carried by said scale, said mask having a. section thereof cut -.respect to said scale to facilitate the use of different directional characteristics of said directional and substantially non-directional antennas in obtaining bearings and direction with respect to predetermined transmitting stations.

2. In direction finders, the combination of a rotatable directional antenna having a metal casing, a substantially circular scaleecarrying member attached to said casing, and a substantially circular ring-like mask having a cut away section to cover selected portion of said scale and fitted to said scale-carrying member and being slidable with respect thereto, said mask being rotatable with said member upon rotation of said directional antenna,

3. In direction finders, the combination of a rotatable directional antenna, scale-carrying means connected thereto so as to be rotatable therewith, an adjustable masking means fitted over said scale-carrying means and having a section thereof cut away to expose not more than half of said scale at any one time; said masking means being slidable with respect to said scalecarrying means.

4. In direction finders the combination of a rotatable directional antenna having a metal casing, a substantially circular scale-carrying member attached to said casing for rotating said antenna, a substantially circular masksnugly fitted to said scale-carrying member, and being slidable with respect thereto for covering selected portions of said scale, said mask being rotatable with said member, and means for locking said 'scale-carrying member against rotation While said mask is rotated. a

- 5. In direction finders the combination of a rotatable loop antenna, a casing for said loop antenna, said casing having a mounting neck for supporting said antenna vertically, a cabinet for supporting said antenna, a scale-bearing member attached to said mounting neck for rotating said loop antenna, a rotatable mask snugly fitted to said scale-bearing member, said mask having a cut-away portion and being adjustable with respect to said scale for exposing only selected portions of said scale, and a lock for holding said loop antenna in a selected position while said mask is adjusted.

6. In direction finders employing a rotatable directional antenna, a substantially non-directional antenna, means connected to said directional antenna and said substantially non-directional antenna for employing said antennas selectively in obtaining bearings or direction and scale mask means for said rotatable antennae-the method of obtaining bearings or determining direction including the following steps: receiving signal energy bi-laterally with said directional antenna, receiving signal energy uni-laterally with both the directional and the substantially non-directional antennas, rotating the directional antenna to determine the number of positions at which high intensity signal energy is received and adjusting the directional antenna to the position at which the lowest of the high intensity signals is received, adjusting the signal output ratio between the antennas so that the lowest of the high intensity signals disappears or becomes very weak, rotating the directional antenna to the position of the highest intensity signal, rotating the mask means of the directional antenna scalemeans while the directional antenna is held stationary to mask the front part of the scale means, disconnecting the substantially non-directional antenna and rotating the directional antenna around until the back part or unmasked part of the scale is in View in the front to adjust the directional antenna in position so that it may be operated as a bi-lateral antenna on the minimum signal indication in the direction of the signal transmitter.

'7. In a direction finder, the combination of a rotatable directional antenna having a rigid casing, a scale-carrying member attached thereto and rotatable therewith, a mask having a cut away portion revealing a section of said scale carried by said member, said mask being slidably engaged by said member and rotatable therewith, and means for locking said member in any selected position.

CHARLES WM. HICKS. 

